This invention relates generally to wireless communication systems. The present invention also relates to integrated circuits (ICs) for basestations and Semiconductor Intellectual Property (SIP) Cores for handset and terminal products. In addition, this invention relates to communications theory, digital signal processing, computer architectures, and silicon engineering to efficiently deliver the highest levels of signal processing performance, as well as flexibility and scalability, for next-generation wireless applications.
Wireless communication has extensive applications in consumer and business markets. Among the many communication applications/systems are: mobile wireless, fixed wireless, unlicensed Federal Communications Commission (FCC) wireless, local area network (LAN), cordless telephony, personal base station, telemetry, encryption, and others. Generally, each of these applications utilizes unique and incompatible modulation techniques and protocols. Consequently, each application may require unique hardware, software, and methodologies for processing digital signals, such as generating the codes required for encoding and for decoding a signal, modulation, demodulation, and other processes. This practice can be costly in terms of design, testing, manufacturing, and infrastructure resources. As a result, a need arises to overcome the limitations associated with the varied hardware, software, and methodologies of processing digital signals in each of the varied applications.
In practice, multiple copies of the same signal are typically received at a communications device. These copies, which are sometimes called multipath components arise because the signals take different paths of different length from the transmitter antenna to the receiver antenna. In the case of a code division multiple access (CDMA) system, it is feasible and advantageous to despread and decode several of the multipath components, realign them so that they are also in phase and combine them to produce a stronger signal. To do this, the base band processor in a CDMA system typically takes the form of a rake receiver that has several fingers, each one of which is a receiver that despreads and decodes one of the multipath components. General information about CDMA systems can be found in J. S. Lee, L. E. Miller, CDMA Systems Engineering Handbook (Artech House 1998); J. B. Groe, L. E. Larson, CDMA Mobile Radio Design (Artech House 2000); and V. K. Gorg, IS-95 CDMA and cdma 2000 (Prentice Hall 2000) all of which are incorporated herein by reference.
Typically, a wireless communication device is organized into two parts, a modem and a codec. These are implemented in an application specific integrated circuit (ASIC) in combination with a digital signal processor (DSP). The ASIC offers the advantage of drawing low power but is inflexible. On the other hand, the DSP provides greater flexibility since it is programmable but it does not offer the low power advantage of the ASIC. It is desirable to obtain the low power benefits throughout the communication device while also obtaining the ability to program it.
Service providers and network operators often need to support multiple standards. Therefore, it is desirable to provide a flexible and programmable communication device suitable for different spread spectrum systems at a minimal development cost.